The Nuclear Regulatory Commission (NRC) is amending its regulations to allow holders of operating licenses for nuclear power plants to reduce the assumed reactor power level used in evaluations of emergency core cooling system (ECCS) performance. This amendment provides licensees the option to apply a reduced margin for ECCS evaluation or to maintain the value of reactor power that had been mandated in the regulation. This action allows interested licensees to pursue small, but cost-beneficial, power uprates and reduces unnecessary regulatory burden without compromising the margin of safety of a facility.